54 lines
1.1 KiB
PHP
54 lines
1.1 KiB
PHP
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<?php
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set_time_limit(0);
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/*
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* Advent of Code 2016
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* Day 5 (part 1 and 2)
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*/
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function calculateHashes($salt, $max = 8) {
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$result = array();
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$count = 0;
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$start = 0;
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$cache_file = md5($salt).".cache";
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if(file_exists($cache_file)) {
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$result = file($cache_file);
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if(count($result) >= $max)
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return $result;
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}
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for($i = 0; $i < 1000000000; $i++) {
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$hash = md5($salt.$i);
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if(substr($hash, 0, 5) === '00000') {
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$result[$count++] = $hash;
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if($count >= $max)
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break;
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}
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}
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file_put_contents($cache_file, implode("\n", $result));
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return $result;
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}
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$puzzle_input = 'reyedfim';
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$hashes = calculateHashes($puzzle_input, 30);
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// Part 1
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$password = '';
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for($i = 0; $i < 8; $i++) {
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$password .= substr($hashes[$i], 5, 1);
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}
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echo "Step 1 Password: $password\n";
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// Part 2
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$password = array_fill(0, 8, '_');
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for($i = 0; $i < count($hashes); $i++) {
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$pos = substr($hashes[$i], 5, 1);
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$char = substr($hashes[$i], 6, 1);
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if (is_numeric($pos) && (int)$pos < 8 && $password[(int)$pos] === '_')
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$password[(int)$pos] = $char;
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}
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echo "Step 2 Password: ".implode($password);
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